This project proposes to quantitate pre-prolactin (pPRL) and pre-growth hormone (pGH) mRNA and to determine their subcellular distribution in different developmental stages of the bovine fetal pituitary. Total cellular, nuclear and polysomal RNA will be prepared from fetal pituitaries ranging from 90 to 260 days of gestation. Pure pPRL and pGH DNA probes will either be synthesized from their respective mRNA templates with reverse transcriptase, or isolated from bovine pituitary cDNA clones, and used in a hybridization assay to quantitate levels of pPRL mRNA or pGH mRNA in the different RNA fractions. In addition, clones complementary to the mRNAs coding for the common alpha and different beta subunits of FSH, TSH and LH will be identified, isolated and used in hybridization assays to quantitate their respective mRNAs in the developing fetal pituitary. While differentiation and development are generally thought to occur as a result of selected and differential expression of the cellular genetic program, it is not clear whether gene expression is always regulated at the level of transcription. Therefore, the goals of this project are to determine: 1) whether mRNAs coding for the pituitary polypeptide and glycoprotein hormones are differentially expressed during development; and 2) whether nuclear restriction of a specific mRNA sequence plays a role in differential expression.